3D Model of Extraction of Oil from North Sea Fields by Supercritical Carbon Dioxide

Abstract

The extraction of North Sea oil from the oil saturated chalk samples by supercritical carbon dioxide was investigated to determine the pressure value, at which the highest amount of oil can be extracted. The pressure of extraction was gradually increased at every next test to check out how the extraction of lighter hydrocarbon fractions at lower pressure affect the oil recovery rate at higher pressure. The first serial test was conducted with three core chalk samples of equal size and each of a weight of 9 g. The samples were naturally saturated with oil at three values of temperature of 50 o , 60 o and 70C. For comparison, the second serial test was conducted with three pure chalk samples of equal size and weight of 26 g saturated with the North Sea oil under vacuum in the laboratory at the same values of temperature. The results of experiments were represented as the surfaces in the coordinates of (Pressure, Amount of extracted oil, Temperature). 3D models revealed that the deviations in the graphs are not occasional. They form wavy surfaces where the folds of waves correspond to hydrocarbon fraction of certain compositions. The highest amounts of oil at all three temperature values in both tests were extracted at 18 MPa in average, where the graphs formed peaks, but the oil was very light, which means that the heavier hydrocarbon fractions were not extracted at such pressure value.